PERSPIRATION. 273 



" In the fourth or American, comprehending all the Americans 

 excepting the Esquimaux, it is almost copper coloured, and in 

 some of a cinnamon, and, as it were, ferruginous, hue. 



" In the fifth or Malaic, in which I include the inhabitants of 

 all the islands of the Pacific Ocean, and of the Philippine and 

 Sunda, and those of the peninsula of Malaya, it is more or 

 less brown, between the hue of fresh mahogany and that of 

 cloves or chestnuts. 



" All these shades of colour, as well as the other character- 

 istics of nations and individuals, run so insensibly into one 

 another, that all division and classification of them must be more 

 or less arbitrary. 



" The essential cause of the colour of the Malpighian mucus 

 is, if we mistake not, the proportion of carbon which is excreted 

 together with hydrogen from the corium, and which, in dark 

 nations, being very copious, is precipitated upon the mucus, and 

 combined with it. n 



" The corium, which is covered by the reticulum and epidermis, 

 is a membrane investing the whole body, and defining its surface ; 

 tough ; very extensible " ; thicker on the posterior part of the 

 trunk and neck than the anterior, and on the outside than the 

 inside of the extremities ; of a fibro-cellular texture ; consisting 

 almost entirely of gelatine; " every where closely compacted, and, 

 as it were, interwoven, especially externally, but more loosely at 

 its internal surface, in which, excepting in a few regions of the 

 body, we generally discover fat." On the outer surface of the 

 corium, we observe innumerable, very minute, soft, erectile pa- 

 pillae, supplied with vessels and nerves. They are far most distinct 

 in the soft part of the ends of the fingers and toes, and upon the 

 palms and soles, and scarcely distinguishable in other parts where 

 the corium is thinner. 



" Besides nerves and absorbents, of which we shall speak here- 



n " I have given this opinion at some length, in my work, De Gen. Human. 

 Varietate Nativa, p. 122. sq. ed. 3. Some eminent chemists accord with me, 

 among whom suffice it to mention the celebrated Humphry Davy, Journals of 

 the Royal Institution, vol. ii. p. 30. In the rete mucosum of the African, the 

 carbon becomes the predominant principle; hence the blackness of the negro.' 

 W. B. Johnson, 1. c. vol. ii. p. 229. 



F. B. Osiander has given an abundance of very careful observations upon the 

 various proportions of the carbonaceous element in the Malpighian mucus. Com- 

 ment, Soc. Reg. Scientiar. Getting, recentiorum, vol. iv. p. 112. sqq." 



T 3 



